1. Field of the Invention
The present invention relates to a golf club shaft.
2. Description of the Related Art
Flex point is known as one of specifications of a golf club shaft. High flex point, middle flex point, and low flex point are known as the flex point.
A shaft having high flex point can suppress an unstable motion of the tip part of the shaft. The shaft having high flex point has excellent operativity and small variation in a hit ball.
Japanese Patent Application Laid-Open No. 9-234256 discloses a golf club shaft which has a grip portion and a tip portion having higher torsional rigidity in a torsional rigidity distribution property line compared to a case the torsional rigidity distribution property line is drawn by a straight line. The golf club shaft has a center portion having higher flexural rigidity compared to a case the property line is drawn in a straight line. Japanese Patent Application Laid-Open No. 10-43333 (U.S. Pat. No. 6,056,648) discloses a shaft having a torsional rigidity sudden-change portion provided on a tip part side of a grip part. Japanese Patent Application Laid-Open No. 2009-219681 discloses a shaft having a steep taper part which is steeply tapered and is provided between a head side small diameter part and a grip side large diameter part.